1. Field of the Invention
This invention relates to improvements in methods and apparatuses for selecting, conveying and storing integrated circuits, and, more particularly, to improvements in methods and apparatuses for facilitating the automatic fabrication of integrated circuit packages or containers.
2. Background Information
In the construction of integrated circuits, typically the integrated circuits are fabricated or processed at a plurality of different workstations or sites. Often the circuits are manually transported between or among the various workstations or sites singly or in groups as the fabrication and testing processes are sequentially performed. In the manufacture of some kinds of integrated circuits for example, a chip or bar may be mounted onto a lead frame or film, which is thereafter mounted onto a base, usually of plastic or ceramic. Finally, a lid or cover is positioned upon and glued or otherwise affixed to the base to completely enclose the integrated circuit chip in a package ready for use.
In many installations, many if not all of the individual fabrication steps has been accomplished automatically, and, with the advent of computer technology, each of the steps has been performed with increasing reliability. Typically in the past each of the steps has been performed at individual work stations with manual inspection of the parts produced at the various stages of construction. A typical integrated circuit package fabrication process in a plastic container (one of the many types to which the invention pertains) includes mounting the integrated circuit chip onto a lead frame to create a combination which can be mounted onto a header bar. This may, for example, be accomplished during a first work shift. The mounted header bars are then generally manually carried in bulk to manual inspection stations. Although ideally immediate inspection of the intermediate header bar work product is desired, as a practical matter, typically inspection may be delayed one or more work shifts. Thereafter, in similar fashion, the inspected parts may be carried in bulk to a bonding station, at which wire leads are bonded to the integrated circuit chip and the lead film. Again, practically speaking, this bonding process, may occur one to one and one-half days after the first inspection, or even later in some cases. After the bonding process, the work product is carried in bulk to a second inspection station at which the product is again inspected, usually 24 hours or so after the bonding process has been completed.
It can be appreciated that due to the large times in the various stages of fabrication before final inspection primarily resulting from the various inspection processes and manual interstation transportation of the devices, if any malfunctions in the equipment or fabrication processes occur, a large number of bad or rejectable integrated circuit products may be constructed before the error can be detected and corrected. This can be particularly expensive in the manufacture of many state-of-the-art integrated circuits such as a 256K bit DRAM, and such complex devices.
In the past, for instance, not untypically in manual processes, overall yields of only about 85 to 90% have been experienced.
Many arrangements for automatically fabricating and bonding semiconductor devices have been advanced. An example of such system can be seen in U.S. Pat. No. 4,301,958, which includes a plurality of workstations interconnected by a vertically oriented magazine into which strips carrying the integrated circuit lead frames are received and dispensed for movement of the frames between workstations, in accordance with a predetermined flow process.